The present invention relates to an apparatus for magnetically storing and retrieving data to and from memory medium.
There is known data storage apparatus having a magnetic head (hereinafter referred to as "head") for magnetically writing and reading data onto and from magnetic memory medium (hereinafter referred to as "medium") such as magnetic tape, magnetic card, flexible disk and hard magnetic disk (hereinafter referred to as "hard disk"). It is necessary to reduce the space between the medium and the head as small as possible in order to increase the recording density or capacity in the data storage apparatus. For this reason, a flying head is utilized to access the hard disk. The flying head is floated from the surface of the hard disk without contacting the hard disk surface by means of flying force due to air flow generated by the rotation of the hard disk.
The minimum spacing attained in the conventional apparatus of the type utilizing the flying head and the hard disk is about 0.2 micron. In addition, the hard disk is comprised of a substrate composed of hard material such as aluminum alloy, aluminum alloy covered with nickel-phosphorus plating film, aluminum alloy covered with alumina, glass, and ceramics so as to reduce waviness and roughness of the hard disk surface. A medium layer and a protecting layer are also flatly and smoothly formed on the substrate. Further, a surface of the head opposed to the hard disk is finished to attain the evenness thereof and to reduce the roughness thereof.
For example, FIG. 2 shows a conventional data storage apparatus of Winchester type utilizing the flying head and the hard disk. The conventional apparatus comprises a hard disk 10 includes substrate 11 and a magnetic medium layer 12, a magnetic head 13, and a gimbal spring 14 for supporting the magnetic head 13.
In the conventional apparatus, the magnetic head tends to come into contact with the medium surface and therefore abraded (head clash) due to protrusion and dust on the medium surface. Moreover, when the rotation of the disk is suspended before starting and after driving, the flying force is not applied to the head to thereby cause friction-abrasion of the head surface. If the dimension of spacing between the head surface and the disk surface is set below the mean free pass of air (about 0.1 .mu.m), collision probability of air particles to the head surface and the disk surface would be reduced to lose the effective flying force. Further, since the flying head surface is formed flat, an edge portion of the head occasionally comes into contact with the disk surface due to even slight inclination of the head to destroy the head and the magnetic medium layer. Such phenomena become more remarkable when the dimension of the spacing is set smaller. If the head surface is not formed flat or even, the dimension of the spacing between the head surface and the disk surface is apt to vary so as to thereby unstabilize the reading and writing of data and to thereby tend to apply concentrated load weight to the disk surface when the head comes into contact with the medium to destroy the magnetic medium layer and the head.